First add the retrobat script to start a direct game

https://retrobat.forumgaming.fr/t2912-startup-launch-game

It´s easy. Follow the instructions.

To hide the desktop we first have to generate a .vbs file inside the retrobat directory

C:\RetroBat\retrobat_shell.vbs

Copia esto:

' C:\RetroBat\retrobat_shell.vbs
Dim fso, sh, ROOT, PLUG, LOG, rc
Set fso = CreateObject("Scripting.FileSystemObject")
Set sh  = CreateObject("WScript.Shell")

ROOT = "C:\RetroBat"
PLUG = ROOT & "\plugins\StartupLaunchGame"
LOG  = ROOT & "\logs\boot_wrapper.log"

If Not fso.FolderExists(ROOT & "\logs") Then fso.CreateFolder(ROOT & "\logs")
Dim logf: Set logf = fso.OpenTextFile(LOG, 8, True)
logf.WriteLine Now & " === Inicio ==="

If Not fso.FileExists(PLUG & "\boot.exe") Then  logf.WriteLine Now & " No existe boot.exe"  sh.CurrentDirectory = ROOT  sh.Run """" & ROOT & "\retrobat.exe""", 0, False  '0 = oculto  WScript.Quit
End If

sh.CurrentDirectory = PLUG
rc = sh.Run("""" & PLUG & "\boot.exe""", 0, True)    '0 = oculto, True = esperar
logf.WriteLine Now & " boot.exe salió con rc=" & rc

If rc <> 0 Then  sh.CurrentDirectory = ROOT  logf.WriteLine Now & " Fallback a RetroBat"  sh.Run """" & ROOT & "\retrobat.exe""", 0, False
End If

Then we generate the log and execute it

Importa este .reg: retrobat_shell.reg

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Winlogon]
"Shell"="C:\\Windows\\System32\\wscript.exe //nologo C:\\RetroBat\\retrobat_shell.vbs"

And finally reboot the pc.